Generally, an automatic dryer is an apparatus to automatically dry the wet laundry cleaned, which is largely classified into a condensing type which circulates the inside air; and an exhausting type which introduces the outside air to the inside.
The automatic dryer of the exhausting type heats the introduced outside air by a heater, and supplies the heated air to the inside of a drum which is in a rotating state, to thereby dry the laundry such as clothes received in the inside of the drum.
FIGS. 1 to 5 illustrate an exemplary electrode sensor provided in a drying drum, and FIG. 3 illustrates a circuit diagram of the electrode sensor.
In the automatic dryer that determines a dryness level with the electrode sensor, two electrodes are separately provided at predetermined portions of the drying drum having the laundry therein, for example, at a lifter or a lower side of a door, for being in contact with the laundry. In this case, as the laundry contacts with the electrodes, a resistance value is changed according to a water content of the laundry.
Accordingly, a voltage value depends on the changeable resistance value. Then, a micom reads the voltage value to thereby determine the dryness level.
That is, if the water content of the laundry is decreased with the progress of drying stroke, the resistance value is increased, and the voltage value is increased in proportion to the resistance value. When the voltage value is constant, the micom regards it as being a drying finish point.
FIG. 4 illustrates the electrode sensor which is formed in an entire length of the lifter. FIG. 5 illustrates an electrode sensor which is formed in a partial portion of the lifter.
When determining the drying finish point based on the dryness level obtained indirectly by the above electrode sensor, it is difficult to obtain the exactness in determination of the drying finish point since the dryness level is obtained based on the resistance value changed by the contact state with the laundry.
Especially, if trying to dry the small amount of laundry by the above electrode sensor, there is a difficulty in ascertaining the exact amount of the laundry. Thus, the laundry may be partially un-dried or over-dried, whereby a power may be consumed excessively.
When drying the large amount of laundry, the discrimination for the dryness level becomes low due to the saturation output value of the electrode sensor.
Furthermore, it is difficult to realize the exact determination for the dryness level since the identical method is applied to the laundry without consideration of the amount of laundry.